The present invention relates to systems and methods for providing interactive content to a remote device and more specifically to systems and methods employing both a managed and an unmanaged network, where the unmanaged network has a high latency and high bandwidth variability.
In cable television systems, the cable head-end transmits content to one or more subscribers wherein the content is transmitted in an encoded form. Typically, the content is encoded as digital MPEG video and each subscriber has a set-top box or cable card that is capable of decoding the MPEG video stream. Beyond providing linear content, cable providers can now provide interactive content, such as web pages, walled-garden content, video games, voice-over-IP (VOIP) telephony services that may include video, interactive catalogs and streaming delivery of audiovisual content including movies, and the like. As the Internet has become more dynamic, including video content on web pages and requiring applications or scripts for decoding the video content, cable providers have adapted to allow subscribers the ability to view these dynamic web pages. In order to transmit a dynamic web page to a requesting subscriber in encoded form, the cable head end retrieves the requested web page and renders the web page. Thus, the cable headend must first decode any encoded content that appears within the dynamic webpage. For example, if a video is to be played on the webpage, the headend must retrieve the encoded video and decode each frame of the video. The cable headend then renders each frame to form a sequence of bitmap images of the Internet web page. Thus, the web page can only be composited together if all of the content that forms the web page is first decoded. Once the composite frames are complete, the composited video is sent to an encoder, such as an MPEG encoder to be re-encoded. The compressed MPEG video frames are then sent in an MPEG video stream to the user's set-top box.
Creating such composite encoded video frames in a cable television network requires intensive CPU and memory processing, since all encoded content must first be decoded, then composited, rendered, and re-encoded. In particular, the cable headend must decode and re-encode all of the content in real-time. Thus, allowing users to operate in an interactive environment with dynamic web pages and other dynamic content is quite costly to cable operators because of the required processing. Additionally, such systems have the additional drawback that the image quality is degraded due to re-encoding of the encoded video.
Satellite television systems suffer from the problem that they are limited to one-way transmissions. Thus, satellite television providers can not offer “on-demand” or interactive services. As a result, satellite television networks are limited to providing a managed network for their subscribers and can not provide user requested access to interactive information. Other communication systems cannot provide interactive content, for example, cable subscribers that have one-way cable cards or cable systems that do not support two-way communications.
The related U.S. patent application Ser. No. 12/489,017 teaches a system and methods for providing one-way broadcast content over a managed network and two-way interactive services over an unmanaged network. However, unmanaged networks may include higher latencies, more dropped packets, and more variable bandwidths than managed networks, precisely because they are not managed by a television operator. Such higher latencies, error rates, and bandwidth variability are detrimental to interactive services. To provide an optimal subscriber experience, many interactive services require high video frame rates and high quality audio, as well as very low data error rates and very low latency, while transmitting across an unmanaged network environment that experiences highly variable transmission conditions. To complicate matters, television providers may wish to save money by reducing the complexity of subscriber client set-top boxes or cable cards, which are produced in much higher numbers than server computers located at a cable head-end. Such “thin” clients may have reduced computing power, and must provide an optimal subscriber experience within a very constrained hardware and software environment.
Methods are known in the prior art to transmit data between computers connected by an unreliable network. One example method uses the User Datagram Protocol (UDP), as first formally defined in Postel, J., Request for Comments 768: User Datagram Protocol (August 1980) (“RFC 768”). UDP provides a procedure for application programs on different computers to send data to each other with a minimum of protocol mechanism. Traditionally, providers of audiovisual content have used UDP for transmitting non-interactive content, such as streaming video, because of the very low latency and low overhead of UDP. However, more recently, security concerns have prompted a large and growing number of television subscribers to place their client devices behind a network firewall. Firewalls may be difficult for subscribers to configure, especially to allow certain UDP connections from a content provider and not other, harmful connections. Further, UDP does not provide reliable data transmission, causing “skips” or other artifacts in transmitted audio or video, and therefore does not meet the requirements for providing an optimal user experience.
The Transmission Control Protocol (TCP), as first formally defined in Information Sciences Institute, Request for Comments 793: Transmission Control Protocol (September 1981) (“RFC 793”), does provide reliable data transmission, but providing interactive services over a TCP network to a thin client is problematic. TCP provides a number of high-level services that UDP does not, such as end-to-end connections, and packet reordering and retransmission. These additional services consume valuable computing resources that are in high demand on a thin client device and introduce retransmission latency into the communication channel. Another problem is that transmitting full-motion video, such as that found in a streaming movie, consumes a great deal of network bandwidth. Some special-purpose systems, such as networked 3D video games, combat this problem by transmitting only game data to a client device and having the client device render the virtual environment. Such solutions are inapplicable to general video applications. Further, the calculation and rendering processes required on the client device consume even more computing resources than simple video rendering alone, making them unsuitable on a very thin client, even for playing video games. Thus, while TCP has several advantages over UDP for transmission of interactive services to subscribers, the thin client requirement makes the provision of these services difficult.